In modern networks, such as Asynchronous Transfer Mode (ATM) networks, the elements of the network use a management information base (MIB) to maintain common status and configuration information. The ATM MIB, for example, holds information concerning virtual path connections (VPCs), virtual channel connections (VCCs), registered services, registered ATM network prefixes and addresses, and capabilities available at ATM interfaces. All of the ATM devices in the network, such as switches and end-systems, use the MIB to determine how to conduct their network communications.
In order to set up and maintain the MIB, the different ATM devices must exchange management information regarding status and configuration conditions. A variety of different methods and protocols for this information exchange have been developed. One commonly-used method is provided in the Integrated Local Management Interface (ILMI) Specification, Version 4.0, published by the ATM Forum Technical Committee (publication no. af-ilmi-0065.00, September, 1996), which is incorporated herein by reference. ILMI supports bi-directional exchange of ATM interface parameters between a pair of connected ATM interface management entities (IMEs), so that each of the pair of IMEs can access the ATM interface MIB of its counterpart. Each pair typically includes a network-side IME and a user-side IME (although within the network there are also symmetric IME pairs). When a network device, such as a switch, has multiple ATM interfaces, it will likewise have multiple IMEs, one for each interface.
When a change occurs in configuration or status information held by one of the IMEs in a pair, it sends a trap packet to its counterpart in order to report the change. Trap packets are the means specified by the Simple Network Management Protocol (SNMP) for reporting extraordinary events in a network. SNMP is defined in Request for Comments (RFC) 1157 of the Internet Engineering Task Force (IETF), and is used by ILMI in management and control operations across ATM interfaces. Ordinarily, when the counterpart IME receives the trap packet, it reads the pertinent information from the sending IME in order to determine the configuration and status changes that have occurred. Trap packets are sent using the User Datagram Protocol (UDP), which generally provides fast service but does not guarantee reliable delivery. Therefore, each IME periodically polls its counterpart in order to ensure that no traps have been missed.
Digital Subscriber Line (DSL) is a modern technology that enables broadband digital data to be transmitted over twisted-pair wire, which is the type of infrastructure that links most home and small business subscribers to their telephone service providers. DSL modems enable users to access digital networks at speeds tens to hundreds of times faster than current analog modems and basic ISDN service. DSL thus opens the most critical bottleneck in local-loop access to high-speed networks, and thus enables ATM service to be extended to client premises equipment (CPE) without requiring major investments in new infrastructure. A range of DSL standards have been defined, known generically as “xDSL,” wherein the various standards have different data rates and other associated features but share common principles of operation.
DSL subscribers are connected to high-speed core networks through Digital Subscriber Line Access Multiplexer (DSLAM) systems. Because of the high cost of network bandwidth, a single DSLAM is typically designed to serve between 100 and 1000 clients and to concentrate their traffic through one or a few network trunks. (In the context of the present patent application, the inverse of the number of clients served by a multiplexer—between 1:100 and 1:1000 in the case of the typical DSLAM—is referred to as its concentration ratio.) Thus, to accord with the ILMI model described above, the DSLAM must maintain as many as 1000 network-side IMEs in order to serve all of its clients. As network use grows in the future, this figure may grow even higher. Concentration ratios of this magnitude were not envisioned when the ILMI standard was developed. Adherence to the conventional ILMI model under these conditions would require both the DSLAM and the CPE to dedicate an excessive amount of computing power to interface management.